The picture presentation period for the subjective assessment becomes important in such a case when the occurrence behavior of picture quality degradation is varying every moment. Subjective tests are carried out for various periods of picture presentation. It is made clear from subjective test results that: (1) observers' direct opinion to presentation period suggests 20-25 sec to be necessary, but (2) indirect results such as variance of opinion score shows 15-20 sec to be necessary. Therefore ,it is concluded that 15 sec is considered minimum and 20 sec desirable

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The human vision system is modelled using the basic theory on figure observation. In this vision model ,It is assumed that the human vision system changes the quantities of blur and vision area depending on presented pictures. This theory reveales that the visual response to sinusoidal waves is deseribed as composed of narrow band pass filter array (multiple channel model). Using this model,experimental results on the rectangular wave response is explained precisely.

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Several recent studies have proposed models for visual motion perception using spatiotemporal filters. Among these, a model proposed by A.B.Watson and A.J.Ahumada model calculates two dimensional velocity, while others infer only one dimensional motion direction. However, the Watson/Ahumada model has limited accuracy for velocity estimation, mostly because it essentially uses only one spatial frequency channel. In human visual motion perception, it has been shown by various psychophysical studies that there are interactions between spatial frequency channels. In the present study, therefore, we propose an improvement of the Watson/Ahumada model by combining outputs from multiple spatial frequency channels for estimation of two dimensional velocity. The effectiveness of this multiple frequency method was demonstrated with moving random dot patterns. The outputs from three channels were additively combined using the following method: The straight lines representing the locus of possible velocity solutions for each spatial frequency channel were first plotted independently on one velocity field, then local velocity was determined by finding intersections of these lines. Combination of three frequency channels using this simple additive method resulted in an improvement of accuracy in velocity estimation. The positive results achieved here indicate that further implementation of more elaborate interactions between channels will provide even better performance.

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Human lipreading abilities were investigated. A VCR (VTR) was used to display a female narrator who spoke 100 Japanese syllables. The subjects were 40 normal adults. They were assigned to one of two narrators and participated in 3 experimental sessions of 100 syllables. The result showed: (a) Although only 15% of the syllables were reported correctly, 80% of vowels and 20% of consonants were read correctly. (b) By overlooking some types of errors, such as confusion within labials, within voiced and voiceless pairs, and so forth, 35% of syllables were recognized correctly. (c) Labials were almost perfectly discriminated from non-labials. (d) Stimulus-response patterns suggested features specific to a narrator as well as some common to narrators. (e) Practice effect were found.

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Some recent studies suggest that ordinary stereophonic system is not sufficient for HDTV. One of the reasons may be localization error between picture and sound which occurs with non-axial viewing. This experiment. is designed to investigate the permissible extent of angular displacement between sound image and picture on the wide screen. The data, which is scaled by the method of successive categories, shows that the extent is about 11 degrees for acoustic engineers and about 20 degrees for ordinary subjects. Based on the results, this paper discusses how many frontal loudspeakers are required for HDTV.

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A new 12- in . -diagonal 3-D plasma display panel with a lenticular sheet has been developed. This display has 640 X 400 We have pixels and a high contrast ratio greater than 150:1. demonstrated that 3-D moving pictures viewed directly without special glasses could be obtained by using the display. Some important aspects of visual characteristics for the 3-D display are also described.

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